C-Kit is the receptor tyrosine kinase for stem cell factor (SCF) and is a member of the subfamily that includes PDGF, CSF-1 and FLT-3/flk-2 receptors (1,2). It plays critical controlling roles in a number of cell types such as hematopoietic stem cells, mast cells, melanocytes and germ cells (3). Upon binding with its ligand, c-Kit receptors are induced undergoing dimerization/ oligomerization and autophosphorylation. Activation of c-Kit results in the recruitment and tyrosine phosphorylation of downstream SH2-containing signaling components including PLCgamma, p85 subunit of PI3 kinase, SHP2 and CrkL (4), which links c-Kit directly to various cell signaling pathways. Molecular lesions that impair the kinase activity of c-Kit are associated with a variety of developmental disorders (5), while mutations that constitutively activate c-Kit can lead to pathogenesis of mastocytosis and gastrointestinal stromal tumors (6). Tyrosine 719 is located in the kinase insert region of the catalytic domain. c-Kit phosphorylated at Tyr719 binds to the p85 subunit of PI3 kinase in vitro and in vivo (7). Recombinant protein corresponding to aa544-976 of human CD117 expressed in Baculovirus infected Sf9 cells Specific Activity: 15U/mg. One unit is defined as the amount of enzyme that will incorporate 1nmol phosphate to the tyrosine substrate per minute at pH 7.4 and 30C. Assay Conditions: Enzyme reaction is conducted at 30C for 30 minutres in buffer containing 40mM Tris (pH 7.4), 10mM MgCl2, 100um ATP, and 0.2 mg/ml poly-(Glu-Tyr) as a substrate. ATP reduction was monitored using ADP-Glo. Application: Useful for the study of enzyme kinetics, screening inhibitors, and selectivity profiling. Storage and Stability: Store at -70C stable for 6 months after receipt. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.
